The correct answers are:
C) logging;
The logging is always a big problem for the forests because large amounts of wood are cut down, and even if there's trees planted on their places, it takes a lot of time for the ecosystem to recover.
D) non-native species;
Some species that are non-native can be very dangerous to the native tree species and contribute to their destruction, so people should be very careful with the introduction of non-native species because of their effects on the environment.
F) overgrazing;
The overgrazing mostly affects the grasslands, but it affects the forests as well because very often the young trees are consumed by the farmed animals, thus stopping the natural process of renewing of the forests.
G) wildfires;
Every year there are lots of wildfires, especially during the summer, some are caused by natural factors, some by people, but whatever way they are caused they are very damaging because it just few hours can destroy very large areas of forests.
